The announcement follows accusations by the authorities that the engine violated US clean laws.

In a statement, the carmaker said it would work on a technical solution for North America versions from 2009 model year onwards to be worked out in conjunction with the US Environmental Protection Agency (EPA) and the California Air Resources Board (CARB).

The updated software will be installed as soon as it is approved by the authorities.

This engine was developed by Audi and is used in the Audi US models A6, A7, A8, Q5 and Q7 from model year 2009 onwards. Volkswagen uses the engine in the Touareg and Porsche has used it in the Cayenne since model year 2013.

Audi said it estimates that the related expense will be in the mid-double-digit millions of euros.

It added that the voluntary sales stop for models with the V6 TDI diesel engine has been extended until further notice.